To study the characteristics of ship airwake, the simplified frigate ship, SFS1 and SFS2, and actual frigate ship were simulated, and the results were used to analyze the characteristics of flow field around the flight deck by comparing with the experimental data in wind tunnel. The centerline surface pressure coefficient and vortex separation off the top of hangar shed and reattached on the flight deck were found by the simulation of SFS1, and the existence of horseshoe vortex on the surface of the flight deck was verified. An example indicates that the blocking of the ship geometry is an important driving force for the vortex separation and shedding. The actual frigate ship with 0° and 30° starboard winds was simulated, and the results showed that the shape and size of the hangar affected the intensity and location of the vortices around the flight deck. In the 0° wind direction, to open the hangar door could improve the flow field status of the flight deck.